Pulverizing apparatus



Dec. 10, 1929. o, CRNG 1,739,213

PULVERIZING APPARATUS Filed 001?. 19, 1926 Patented De 10, 1929 UNITED STATES PATENT oFFI cr.

OLLISON CRAIG, OF WORCESTER, MASSACHUSETTS, ASSIGNOR TO RILEY STOKER COR- YORATION, OF WORCESTER, MASSACHUSETTS, A CORPORATION OF MASSACHU- SETTS PULVERIZING APPARATUS Application filed October-19, 1926. Serial No. 142,730.

This invention relates to pulverizing apparatus, and more particularly to an apparatus which is adapted to pulverize and mix two materials.

It is often desired to pulverize and mix two fuels, such as anthracite and bituminous coal, and to transport the mixture to a furnace for combustion. This mixture is required because it is diflicult to burn pulverized anthracite coal alone. Such a fuel has a low percentage of volatile matter, but this trouble can be overcome by mixing bituminous coal with the anthracite. It is found, however, that such different materials have radically different physical characteristics and so need difierent treatment in pulverization. They need to be pulverized either in different types of machine or in similar machines having different arrangements and proportions for the pulverizing elements. This is advisable 'ifiorder to obtain the maximum efliciency in the pulverizing operation and to insurea long life of service of the apparatus used to pulverize the fuel. Sim1larly, it is often desirable to obtain a uniform mixture of two powders which require different treatment in pulverization.

It is accordingly the main object of my invention to construct a pulverizing apparatus in which different materials may be pulverized independently of each other and then mixed.

A further object is to provide an apparatus which will pulverize diiferent materials at independently regulatable rates and then thoroughly mix them, and in which each ma terial is acted upon by separate pulverizing elements particularly adapted to that material.

' It has been found that in increasing the size and capacity of a pulverizing apparatus, a point is soon reaehedwhere the efficiency begins to decrease, though the opposite is usually the case with the drivin motor. In the past, when one machine lac ed the desired capacity-(two separate machines have been used, each driven by its-individual motor, but

. 'this ha's resulted in a waste of power.

It therefore a further object of my invention to produce a pulverizing apparatus which will have a large capacity and high efficiency, and which may be driven by a motor of an etficient size.

tVith these and other objects in view, as will be apparent to those skilled in the art, my invention resides in the'combination of parts set forth in the specification and covered by the claims appended hereto.

In accordance with my invention, I provide separate pulverizing devices, each of which is fed independently of the other, and connect them directly with a device which takes the separately pulverized materials and mixes them intimately. The pulverizing devices are preferably fed by separately and independently regulatable feeding devices arranged to feed materials at rates which may be varied at will. The mixing device may consist of a fan arranged to propel the material, after mixing it, to any desired point. While the invention may be embodied in various forms of apparatus, I have illustrated in the drawing a compact and simple type which may be driven from a single source of power and yet will handle different types of material at the same time and mix them read- 1 y.

In the drawings, in which like reference numerals indicate like parts:

Fig. l is a side elevation of one embodiment of my invention, with parts broken away for clearness of illustration;

Fig. 2 is an end elevation of the apparatus illustrated in Fig. 1, the feeding device being shown in section;

Fig. 3 is a horizontal section through a feeding device; and

Fig. 4 is a detail showing the arrangement of the swing hammers.

I The embodiment of my invention illustrated is an apparatus particularly adapted for the pulverization of coal. It comprises two pulverizing devices located in separate chambers which communicate directly with a mixing chamber, shown as a fan casing. The pulverizing devices may be of radically different types and construction or of the same type but different in size or arrangement of parts, but they are illustrated as alike, for the sake of simplicity of illustration. In the form shown, there is a single casing so arranged as to provide at its ends pulverizing chambers -1() and 11, joined by central passages 12'and 14 respectively to a central fan chamber 16. Each pulverizing chamber is provided with an inlet 18 for the material to be pulverized, and air may be admitted as desired with the material, or an additional air inlet 19 may be arranged in the casing wall.

The fan chamber has a peripheral outlet 20 for the discharge of the powdered material, which is borne on the air current propelled by the fan. A shaft 21 extends centrally through the casing and is rotatably mounted in suitable bearings 22 at each end thereof.

Mounted on the shaft 21 within the central chamber 16 is a fan 24. This fan serves both as a mixing device and as a means of removing the pulverized material from each of the pulverizing chambers. As will be understood, the fan is so constructed as to draw air currents from the central portions of the pulverizing chambers, and these air currents with their burdens of dust will mingle intimately and be forced outwardly through the exit pipe 20 to the furnace burner, a storage bin, or other suitable point of delivery. It can also be seen that the amount of air drawn from each pulverizer will depend upon the regulation of air admitted thereto, so that the final mixture will depend on the regulation of the initial pulverizing units, the fan serving merely to mix and propel what is delivered to it.

Of the various types of pulverizer suitable for my purposes, I have chosen to illustrate the impact type comprising revoluble beaters arranged to break the material by impact and attrition. These devices may be alike in construction, hence but one has been shown in detail, but it will be understood that they need not be alike and may be constructed as best suited for the particular types of material to be pulverized. I prefer however to have them of the same type as illustrated, but to make variations in size or in the arrangement and shape of the various impact members, as desired.

The form illustrated comprises a two zone pulverizer having swiii hammers to give a preliminary pulverization to the material and pegs arranged to finely grind it as it is drawn by the fan towards the central outlet against the action of centrifugal force set up by the revolving impact .iembers. As shown, the pulverizin device in chamber 10 comprises a flange hub 30 keyed to the shaft 21 and having a series of swing hammers 3Ipivotally attached to the hub 30 by bolts 32. These hammers are surrounded by a perforated grid34 mounted on the casing wall. The openings in the grid may be large or small and these may be spaced and located as desired. 'A disk 36 is fixed to hub 30 by the bolts 32- and extends nearly to the periphery two zones connected by an annular passage.

The impact members in the second zone com-' prise a number of rows of revoluble impact pegs 38 suitably fastened on the side of the disk. Cooperating with these are stationary pegs 40 on the casing wall. The pegs are preferably mounted in the manner disclosed in the patent to Riley No. 1,576,472. It will therefore be seen that material fed through openin 18 centrally into the first grinding zone Wlll be crushed by the hammers 31 and then be drawn radially and inwardly between the rows of pegs 38 and 40 and there pulverized finely. Coarse material will be continuously-hurled back by the pegs towards the casing periphery until it is so fine that the fan can draw it as a dust cloud towards and through the outlet pipe 12.

Suitable feeding devices are arranged to supply material at regulatable rates to chambers 10 and 11, although broadly considered the material may be introduced in any suit able Way. Such an apparatus may comprise a horizontal disk shaped table 45, rotatably mounted Within acasing 46 on a vertical shaft 48. This shaft is supported in suitable bearings 50 and 51, and is slowly rotated by a worm gear 54 fixed thereon and driven by a Worm 55. This worm may be provided with a pulley 56, and may be conveniently driven directly from the pulverizer shaft 21 by a belt 58 which passes through an opening 60 in the pedestal 61. A stationary hopper 63 is mounted on the casing 46 above the table 45, and this hopper is provided with an opening 65 in one side. To assist in rotating the material in the hopper, an agitator 66 may be suitably mounted on the upper end of shaft 48. In order to regulate theamount of material escaping through the opening 65, I provide an adjustable scraper 68 which is supported in substantial contact wih the top surface of the table and is arranged to sweep a desired amount of material from the table. The scraper 68 has an extension threaded internally and mounted for adjustment on a horizontal shaft 70 externally threaded on its intermediate portion. This shaft is rotatably mounted in hearings in the casing 46, and is prevented from longitudinal m vement by collars.72 and 73. The shaft is conveniently rotated by a handwheel 75. Hence by turning the shaft the scraper is moved to catch more or less material on the table. An inclined chute 77 is arranged to conduct the material swept from the table 45 to opening 18 in the pulverizer chamber.

The operation of the apparatus will now be apparent from the above disclosure. The shaft 21 is rotated by any suitable source of power. Material is placed in the hopper 63 in each feeder and is rotated by the agitator 66 and table 45. The portion caught by the sired rate depending on the position of the scraper, as determined by the manual control of the handwheel 75. The material passes down the chutes 77 into the chambers 10 and 11. It is first coarsely pulverized by the revolvin swing hammers 31, and passes through the openings in the grid 34. The suction of the fan 24 draws the material around the outside of the disk 36 and then past the pegs 38 and 40, which cause fine pulverization thereof. The fine material travels to the passage 12 and into the fan chamber 16, and the pulverized materials from the two separate chambers 10 and 11 are thus thoroughly mixed by the action of the fan 24, and discharged through outlet 20.

It will be apparent to those skilled in the art that this invention provides numerous advantages not heretofore available. The pulverized devices in chambers 10 and 11 may each be especially constructed and proportioned for the particular material being pulverized. A thorough mixture of the fine material may be brought about by the fan 24. The machine is more eflicient than a pulverizer which has only one pulverizing chamber. The capacity is twice that of such a pulverizer, and yet no additional shaft, bearings, or fan are required. Because of the increased capacity, a motor of a more efficient size may be utilized. The cost for a given capacity is materially reduced, and this applies to the motor as well as the pulverizer.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. A pulverizing apparatus comprising separate pulverizing devices, separately regulatable means for feeding pulverizable materials to said pulverizing devices, whereb said materials are independently pulverized in desired proportions, and a single mixing device connected with both of the pulverizing devices and arranged to receive the materials therefrom and mix them intimately.

2. A pulverizing apparatus comprising walls forming two pulverizing chambers connected with a fan chamber therebetween, a rotatable shaft extending centrally through said chambers, two separate pulverizing heater devices mounted on the shaft in the pulverizing chambers, means for feeding pulverizable materials to said devices for independent pulverization, a fan mounted in said fan chamber between said pulverizing devices for delivering material from the apparatus, and means providing a common peripheral outlet from the fan chamber.

3. A pulverizing apparatus comprising a separately regulatable feeding device for each pulverizing chamber and means permitting air to be introduced to each pulverizing chamber, whereby materials may be pulverized separately in independently regulatable amounts and then mixed in the fan chamber.

4. A pulverizing device comprising walls defining two spaced pulverizing chambers and a common fan chamber therebetween which communicate centrally, a revoluble beater device in each pulverizing chamber, a mixing fan in said fan chamber, and a discharge conduit leading from the periphery of the fan chamber. 5. A pulverizing device comprising walls defining two spaced pulverizing chambers and a common fan chamber therebetween which communicate centrally, a revoluble beater device in each pulverizing chamber, a mixing fan in said fan chamber, means for feeding coarse material in separately regulat able amounts to each of the pulverizing chambers, and a discharge conduit leading from the periphery of the fan chamber.

6. A pulverizing device comprising walls defining two spaced pulverizing chambers opening into a common fan chamber, a shaft disposed centrally of said chambers, revoluble pulverizing beaters and a fan mounted on said shaft in the pulverizing and fan chambers respectively, means forming separate inlets to the pulverizing chambers for coarse material and air, and a single discharge conguit leading peripherally from the fan cham- 7. A pulverizing apparatus comprising a casing having two pulverizing chambers connected centrally with a fan chamber, two separate revoluble pulverizing beater devices within the pulverizing chambers, a feeding device for feeding pulverizable material independently to each of said pulverizing chambers, manually controlled -means for regulating the amount of material fed by each feeding device, a discharge conduit leading from said fan chamber, and a common fan for Withdrawing pulverized materials from both of said pulverizing chambers, thoroughly mixing them, and delivering the mixture to said discharge conduit.

Signed at Worcester, Mass, this 16th day of October, 1926.

- OLLISON CRAIG.

Walls forming a central fan chamber and a 

